title: Postural muscle onset and voluntary movement in the elderly.
abstract: In young and elderly subjects, push and pull arm movements were executed during sitting or standing, under both simple reaction (SR) and choice reaction (CR) conditions. The combined reaction time (RT) results showed that CRT was larger than SRT in both groups. While sitting, the young group exhibited only slight change in RT, whereas the elderly group showed sizeable RT decrease. During standing, for the SR condition, the elderly's RTs were slightly slower than the young's; in contrast, for the CR condition, the elderly's RTs were substantially slower. Further, when the activation of ankle-stabilizer muscles was examined, it was found that postural muscle onset was essentially the same under both conditions. Focal-muscle onset and reaction time, under the choice condition, however, was sensitive to age-related differences. When these data are taken together, they suggest that the elderly may have an impaired postural system which is slow to stabilize the body prior to movement initiation.
authors.affiliation: Motor Behavior Laboratory, University of Wisconsin-Madison 53706.
authors.forename: G E
authors.initials: GE
authors.lastname: Stelmach
authors.forename: L
authors.initials: L
authors.lastname: Populin
authors.forename: F
authors.initials: F
authors.lastname: Müller
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D001132:Arm; D002755:Choice Behavior; D006801:Humans; D009068:Movement; D024510:Muscle Development; D009132:Muscles / Q000502:physiology*; D011187:Posture